Proverbs 30:15-16

Note the numeration mounting to a climax, the two, the three, the four (Amos 1:3 etc.). The word rendered “horseleach” is found nowhere else, and its etymology is doubtful; but there are good grounds for taking the word in its literal sense, as giving an example, in the natural world, of the insatiable greed of which the next verse gives other instances. Its voracious appetite is here represented, to express its intensity, as two daughters, uttering the same ceaseless cry for more.

Proverbs 30:16

The grave - Hebrew שׁאול sh^e'ôl. The “Hell” or Hades of Proverbs 27:20, all-consuming yet never full.